Q6 / 180 · COMEDK 2024 (Morning Shift) · Chemistry
Identify the product [D] formed when Reactant [A] $(M M 78 \mathrm{~g} / \mathrm{mol})$ undergoes the series of reactions shown
- Am-Cresol
- Correct answerBBenzoic acid
- Co-Cresol
- Dp-Cresol
Solution
The reactant [A] has a molar mass of $78$ g/mol, which corresponds to benzene ($C_6H_6$).
In the first step, benzene reacts with methyl chloride ($MeCl$) in the presence of a catalyst (Friedel-Crafts alkylation) to form toluene ($C_7H_8$).
In the second step, toluene reacts with $3$ moles of $Cl_2$ at $385$ K. This is a free-radical side-chain chlorination reaction, which replaces the three hydrogen atoms of the methyl group with chlorine atoms, yielding benzotrichloride ($C_6H_5CCl_3$) as product [C].
In the final step, benzotrichloride reacts with aqueous sodium hydroxide ($NaOH_{(aq)}$). The three chlorine atoms are replaced by hydroxyl groups to form a gem-triol intermediate ($C_6H_5C(OH)_3$), which is unstable and loses a water molecule to form benzoic acid ($C_6H_5COOH$) as product [D].
Answer: Benzoic acid
In the first step, benzene reacts with methyl chloride ($MeCl$) in the presence of a catalyst (Friedel-Crafts alkylation) to form toluene ($C_7H_8$).
In the second step, toluene reacts with $3$ moles of $Cl_2$ at $385$ K. This is a free-radical side-chain chlorination reaction, which replaces the three hydrogen atoms of the methyl group with chlorine atoms, yielding benzotrichloride ($C_6H_5CCl_3$) as product [C].
In the final step, benzotrichloride reacts with aqueous sodium hydroxide ($NaOH_{(aq)}$). The three chlorine atoms are replaced by hydroxyl groups to form a gem-triol intermediate ($C_6H_5C(OH)_3$), which is unstable and loses a water molecule to form benzoic acid ($C_6H_5COOH$) as product [D].
Answer: Benzoic acid
Hence, the correct answer is option: 'B'.